This invention relates generally to lifts for watercraft and more particularly concerns air flow controllers used to raise and lower pneumatically operated lifts for watercraft.
In some known air flow controllers, when the watercraft is being lowered into the water, air exiting the pontoons passes through the motor of the controller. However, water may also pass through, and possibly damage, the motor. A manually operated dump valve is sometimes used to release the air from the pontoons without permitting water to pass through the motor, but this necessitates the manual operation of both the main controller valve and the dump valve to operate the system.
One solution to the multiple manual operation problem is the use of three valves in conjunction with the controller manifold including a main valve between the manifold and the pontoons, a dump valve between the manifold and the atmosphere and a check valve between the manifold and the motor. One manual operation is required to open or close the main valve. When the motor is not running, the dump valve and check valve are automatically opened and closed, respectively, to pass the air and water to the atmosphere to lower the lift if the main valve is opened. When the motor is running, the dump valve and check valve are automatically closed and opened, respectively, to force air into the pontoons to raise the lift if the main valve is opened. While this type of controller eliminates the need for multiple manual valve operations, it requires three rather than two valves.
Another solution to the multiple manual operation problem is to use a three-way valve. In its first position, the valve connects the pontoons to the motor. In its second position, the valve connects the pontoons to the atmosphere. In its third position, the valve disconnects the pontoons from both the motor and the atmosphere. While this type of controller eliminates the need for multiple manual valve operations and reduces the number of valves required, it necessitates the use of a comparatively expensive three-way valve and creates valve orientation and air flow efficiency problems.
It is, therefore, an object of this invention to provide an air flow controller for lifts for watercraft. Another object of this invention is to provide an air flow controller which prevents backflow of water into the controller motor. It is also an object of this invention to provide an air flow controller which requires only one manual valve operation to initiate raising or lowering of the lift. Still another object of this invention is to provide an air flow controller which does not require any three-way valves for its operation. A further object of this invention is to provide an air flow controller which requires less than three valves for its operation.